While I can not speak to the law in California, generally if your grandfather passed with a Will, then the executor had a duty to file the Will with the probate court in the county where your grandfather lived. The Will would become a public document after your grandfather passed away and it was filed. So, you could go up to the clerk's office at the probate court and ask to see the file Most likely, the name of the firm who wrote the Will and Trust will be stamped on the document. Also, you may be able to find out if the executor hired the same lawyer or a different firm to help with distributing the property in the estate.
With regard to the Trust, in some jurisdictions, as a beneficiary, you are entitled to see that portion of the Trust that pertains to you, though not necessarily the whole document. As the other attorney mentioned, many Trusts contain provisions stating that the beneficiaries are entitled to receive an annual accounting of how the trust assets are being managed. However, usually those accountings are only required once a year. So depending when your grandfather passed, you may be in for a wait. You may want to consult an attorney to request assistance in sending a letter to the executor and/or lawyer who wrote the Trust requesting that the executor send you a copy of the trust, an accounting and a list of the trust assets.
The California probate code requires that whomever is in possession of an original will must file it for safekeeping with the court in county of the decedent resided. The code also provides that upon the death of the settlor/trustor when the trust becomes irrevocable, the trustee must give notice to all beneficiaries. If a petition for probate has been filed, you should receive notice of the petition and date of hearing. That notice should also identify the attorney for the petitioning executor/nominee. You also have a right to know what the trust assets are. You should check with the probate court in the county in which your grandfather lived to see if a will has been lodged for safekeeping and if a petition for probate has been filed.
If all that fails, I suggest that you contact a competent lawyer to assist you.
DISCLAIMER: The response herein is not legal advice and does not create an attorney/client relationship or any right of confidentiality between you and the responding attorney. These responses are intended only to provide general information about perceived legal issues within the question. Each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer is not a substitute for competent legal advice from a licensed attorney that practices in the subject area in your jurisdiction and who is familiar with your specific facts and all of the circumstances.